Process for producing an antistatic finish on hydrophobic materials



United States Patent 3,258,358 PROCESS FOR PRODUCING AN ANTISTATIC FINISH 0N HY DROPHOBIC MATERIALS Sidney Cohen, Fair Lawn, N.J., assignor, by mesne assignments, to Millmaster Onyx Corporation, New York, N .Y., a corporation of New York No Drawing. Filed Apr. 10, 1964, Ser. No. 359,554 8 Claims. (Cl. 117-1395) This application is a continuation-in-part of application Serial No. 268,590 filed March 28, 1963, now abandoned.

The present invention relates to a new process for imparting a durable antistatic finish to hydrophobic textile materials such as polyamides, polyester, polyacrylonitrile, polypropylene and polyvinyl chloride materials, in the form of fiber, yarn, woven or knitted goods, films and foams. It also relates to hydrophobic materials treated so as to eliminate or greatly reduce their tendency to accumulate electrostatic charges, and which will retain this antistatic property after repeated launderings and/ or drycleanings.

Synthetic hydrophobic textile materials of great variety are available on the market today. These include polyesters, such as Dacron of E. I. du Pont de Nemours and Company and Fortrel of the Celanese Corp; polyamides, such as Nylon of the E. I. du Pont de Nemours and Company, Chemstrand, and Enka Corp; polyacrylonitriles, such as Orlon of E. I. du Pont de Nemours and Company and Acrilan of Chernstrand Corp; polypropylenes, such as Herculon of the Hercules Chemical Corp.; and polyvinyl chloride copolymers, such as Dynel of Union Carbide Company and Verel of Eastman Company. All of the above types of synthetic hydrophobic materials suffer from the disadvantageous property of a high degree of surface electrical resistivity. This leads to the accumulation of electrostatic charges on the materials when they are subjected to the friction of normal processing or finishing operations on the textile materials or to the friction developed during normal wear of articles manufactured from such textile materials. This property leads to problems in processing, the static charges developed causing adherence of the textile material to other surfaces, interfering with controlled passage of the material through the processing and finishing machinery. It also produces discomfort when garments manufactured from such materials are worn, especially in atmospheres of low humidity, the static charges developed causing failure of the garment to drape and leading to clinging of the garment to the skin or other materials with which it is in contact. Furthermore, the accumulation of electrostatic charges is extremely hazardous when garments made of such materials are worn in potentially explosive atmospheres, such as hospital operating rooms, mines, and certain industrial operations, since the accumulated electrostatic charge may discharge to the atmosphere by sparking and lead to fire or explosion.

It is an object of this invention to provide a process for treating hydrophobic textile materials so as to greatly increase their surface electrical conductivity without altering any of their advantageous properties.

It is a further object of this invention to provide new compositions of matter comprising hydrophobic polymeric materials treated by the above-mentioned process so that they possess antistatic properties durable to repeated launderings and dry cleanings.

According to the present invention, a durable antistatic finish for synthetic hydrophobic polymeric materials is obtained by applying to the said material a composition containing two essential ingredients: (1) a water- "ice soluble polymer made by condensing an aliphatic primary mono amine with a nitrogen-alkylating diester of a polyethylene glycol, such, for example, as a polyethylene glycol dichloride, and (2) a curing agent for insolubilizing the above water-soluble polymer consisting of a polyaziridinyl compound. The solution containing the above ingredients is adjusted with an acid such as muriatic acid to a pH below 7.0 and applied to the hydrophobic material by any convenient means, such as by padding, spraying, or brushing. The treated material is then dried for a short time at temperatures above 220 F.

The water-soluble poly tertiary amines useful in the practice of this invention are prepared by reacting an alkylating diester of a polyethylene glycol with an aliphatic primary monoamine as fully described in Tesoro et al. US. Patent 3,070,552, issued December 25, 1962, and assigned to Onyx Chemical Corporation.

Depending upon the reaction conditions, when the intermediate polyethylene glycol alkylating diester is a polyethylene glycol dichloride, as shown in the cited patent, the terminal end groups of the polymer may be either secondary amino radicals derived from the primary aliphatic amine used as an intermediate or organically bound chlorine originating with the intermediate dichloride. As described in US. Patent 3,070,552, the alkylating diesters which are used as intermediates in preparing the polymeric tertiary amines herein employed correspond to the general formula:

wherein X may be the ester forming residue of an inorganic acid or of an organically substituted sulfuric, phosphoric, or sulfo-nic acid, for example, Cl, Br, I, -CH3SO3, OSO3H, CH3C6H4SO3 and the like. is apparent that the polymeric tertiary amines may, therefore, contain end groups originating with the intermediate alkylating diester, other than onganically combined chlorine, corresponding to the end groups, X, present in the intermediate diester.

The water-soluble poly tertiary amines useful in the practice of this invention may be represented by the general formula:

YCH OH2(O CHIC H9130 R20) OHaCHzOhCHzCHgwhere Y and Y are members of the group consisting of HNR -(i.e. a secondary amino radical derived from the intermediate primary amine wherein R is an alkyl, alkenyl, or hydroxyalkyl radical containing from 1 to 22 carbon atoms, preferably methyl, ethyl, or hydroxyethyl) and the ester-forming residue, X derived from the intermediate alkylating polyethylene glycol diester as set forth in the preceding paragraph; R is a divalent organic radical such as, for example, a glycol radical, a dibasic acid radical OCACO, where A is the intermediate divalent radical of the disbasic acid or a diurethane radical OCNHANHCO where A is again an intermediate divalent radical of the diurethane; m and n are average numbers between 3 and 40; and p is an integer having a value of at least 1.

The polyaziridinyl compounds useful as the second component of the treating bath are organic compounds containing at least two aziridinyl groups and at least one hydrophylic group sufficient to confer water-solubility or ease of emulsifiability in water on the molecule, such hydrophylic group or groups being non-reactive with the azi-ridinyl group. Among the hydrophylic groups suitable for this purpose are the carbamido and oxo, as well as sulfide, sulfone, and polyether groups. Examples of polyaziridinyl compounds useful in the carrying out of this invention are tris-l-aziridinyl phosphine oxide; trison, OH: I l 0%: \C Hg where Z is the di-valent radical of polyethylene glycol 400 derived by elimination of hydroxyl groups.

It has also been found that a further increase in the durability of the antistatic treatment to laundering may be achieved by including in the treating formulation containing the polymeric amino compound and the polyaziridinyl compound, a thermosetting resin-curing catalyst of the metal-salt type. These catalysts are well known in the art of the thermosetting resin treatment of textile materials and include compounds such as zinc nitrate, zinc fluoborate, aluminum chloride, etc. and mixtures of such inorganic salts with organic acids such as maleic acid or acetic acid.

The process of this invention has definite advantages over other antistatic processes and antistatic agents now used in the textile and related industries. Most of the treatments are of only a temporary nature, the finish 3 provided for the hydrophobic material lacking durability to laundering and/or dry cleaning, or have the disadvantages of imparting an unpleasant hand to the goods or leaving the goods discolored after treatment or subject to discoloration on exposure to the atmosphere during normal use. These disadvantages are eliminated in the present process.

The following examples are illustrative embodiments of the invention. In the examples, antistatic properties were determined by measuring the surface electrical resistivity of the treated fabrics at 25% relative humidity by Standard Test Method 76-1959 of the American Association of Textile Chemists and Colorists, the resistivity being expressed as the logarithm of the specific resistivity, log R. Fabrics with a log R value of less than 12.9 at 25% relative humidity, are considered to have satisfactory antistatic properties, since cotton, which does not exhibit the accumulation of electrostatic charges, has a log R value of approximately 12.9 at 25-30% relative humidity. All launderings described in the examples were carried out in a Westinghouse Commercial Laundromat at 140 F. using a 6-lb. load and sufiicient Tide detergent to give an adequate foam level, followed by drying the samples in an automatic tumble-dryer. Dry cleanings were carried out by tumbling the fabric in a glass jar with Stoddard solvent for one hour and then drying.

Applications of treating compositions to textile fabrics were made by impregnating the fabric with the treating solution in a Butterworth Laboratory 3-roll padde-r, placing the fabric on a pin-frame and drying in'a circulating air oven.

Example 1 An aqueous solution was prepared containing 35% by weight of a polyamine made in accordance with Example 10 of US. Patent No. 3,070,552 and 2.1% of Chemirad APO (an 85% solution of tris-l-aziridinyl phosphine oxide supplied by the Chemirad Corp, East Brunswick, New Jersey) and adjusted with hydrochloric acid to a pH of 5.5. The solution was used to treat Dacron taifeta (Testfabrics, Inc., Style 709), and the impregnated sample was dried 2 minutes at 220 F. and then 4 minutes at 300 F., resulting in a gain of 2.0% of solid antistatic composition. The goods had a pleasing hand and showed no discoloration. The fabric, designated as Sample A, was tested and found to have antistatic properties durable to laundering as shown in Table I, and durable to dry cleaning, giving a log R of 9.8 after 10 dry cleanings.

Example 2 The process of Example 1 was repeated, except that the Chemirad APO was omitted from the treating solution. The treated fabric, designated as Sample B, was found to have satisfactory initial antistatic properties, but to lose this property on laundering.

Example 3 The process of Example 1 was repeated except that the treating solution consisted only of 2.1% Chemirad APO adjusted to pH 5.5 with hydrochloric acid. The treated fabric showed slight initial antistatic activity and lost the activity on laundering. The treated fabric is designated as Sample C in Table I.

Example 4 An aqueous solution containing 20.0% of a polyamine made in accordance with Example 10 of U.S. Patent No. 3,070,552 and 1.2% Chemirad APO adjusted to pH 5.5 with hydrochloric acid was used to impregnate an Orlon fabric (Testfabrics, Inc., Style 856). After drying for 2 minutes at 220 F. and. 4 minutes at 250 F., the treated fabric, designated as Sample D, was found to exhibit durable antistatic properties.

Example 5 An aqueous solution was prepared containing 26.8% of a polyamine made in accordance with Example 10 of US. Patent No. 3,070,552 and 1.55% Chemirad APO, adjusted to pH 5.5 with hydrochloric acid. A nylon taffeta (Testfabrics, Inc., Style 302A) was impregnated with this solution and dried for 2 minutes at 220 F. and 4 minutes at 250 F. The treated fabric, designated as Sample E, had durable antistatic properties.

Example 6 An aqueous solution was prepared containing a polyamine made in accordance with Example 10 of U.S. Patent No. 3,070,552 and Chemirad BHE, 1,6-bis-(N-ethylenecarbamido) hexane, in an active ratio of 4 to 1, adjusted to a pH of 5.5 with mun'atic acid. The total solids content of the solution was adjusted to give a solids addon of 2.0% on the fabric to be treated, the concentration of the treating bath therefor varying with the percentage of wet pick-up of the different fabrics. This mixture was applied to the Dacron, cotton and nylon fabrics described above, and all were dried for 2 minutes at 220 F. and 4 minutes at 250 F. The treated samples were designated as follows:

Dacron-Sample F OrlonSample G NylonSample H All were found to exhibit durable antistatic activity.

Example 7 A solution containing only 1.75% Chemirad BHE was used to treat Dacr-on taffeta, dried 2 minutes at 220 F. and 4 minutes at 250 F. The treated fabric, designated as Sample I, exhibited weak antistatic activity which was lost on laundering.

Example 8 An aqueous solution was prepared containing 9.4% of a polyamine made in accordance with Example 10 of US. Patent No. 3,070,552, 0.58% Chemirad APO, and 0.15% of a nonionic wetting agent, the condensation product of TABLE I.ELECTRICAL RESISTIVITY OF FABRICS (LOG R) Number of Launderings Sample Example 9 An aqueous solution was prepared containing 2.75% of a polyamine made in accordance with Example 10 of US. Patent No. 3,070,552, 0.16% Chemirad APO, and i 0.10% Zinc nitrate, the solution being adjusted to a pH of 5.0 with hydrochloric acid. A fabric of Acrilan 16 V was impregnated with this solution and dried for 2 minutes at 220 F., then 5 minutes at 250 F. The treated fabric exhibited satisfactory antistatic properties after 30 launderings, having a log R value less than 12.9 at 25% relative humidity.

In the practice of this invention, advantageous antistatic properties may be imparted to hydrophobic polymeric mate-rials by applying 0.5% to 5.0% of total treating bath solids to the material. The ratio of active material of the polyamine portion of the composition to the active material of the polyaziridinyl compound may be varied over a wide range, preferably from a ratio of 20:1 to 3:2, depending upon the specific material being treated and the degree of durability of antistatic properties desired. The total solids add-on of antistatic composition may be varied from 0.5 to 5.0%, again depending on the level of durability desired. In general, applications of 1.0 to 2.0% d-ry pick-up at polyamine/aziridinyl active ratios of 9:1 to 4:1 are sufiicient to impart high antistatic effects of satisfactory durability to laundering and dry cleaning to all of the common synthetic hydrophobic textile materials.

As hereinabove set forth, the polyamino compounds used in this invention contain both tertiary amine groups in the chain and terminal end groups which may be secondary amino, chloro, or other radicals introduced by the alkylating diesters employed as intermediates in their manufacture. The nature of the reactions which can occur, during curing, between these various active sites of the polyamino compounds and compounds containing a plurality of aziridinyl groups is not understood at this time and the composition of the products formed cannot, therefore, be defined. Hence, my invention is not limited 6 to a specific structure of insoluble, durable antistat so produced.

I claim:

1. The process of imparting durable antistatic properties to a shaped hydrophobic polymeric material for reducing the tendency of the material to accumulate static electricity which comprises applying to the hydrophobic material an aqueous composition containing: (A) a soluble polytertiary amine having the general formula wherein Y and Y are members of the group consisting of (a) HNR wherein R is selected from the group of alkyl, alkenyl, and hydroxyalkyl radicals having 1 to 22 carbon atoms, (b) the ester forming residue of an inorganic acid, and (c) an organically substituted sulfuric, phosphoric and sulfonic acid, and (d) a halogen; R is a divalent organic radical; m and n are average numbers between 3 and 40; and p is an integer of at least 1, and (B) an organic compound containing at least two aziridinyl groups and at least one hydrophilic group sufificient to impart water solubility or case of emulsifiability in Water to said compound, said hydrophilic group being unreactive with the aZi-ridinyl groups, the ratio of the said polytertiary amine to said organic compound being within the range of from 20:1 to 3:2 respectively, and the total amount of said components added to the said shaped hydrophobic polymeric material being within the range of from 0.5% to 5.0% by weight; the pH of the aqueous solution being adjusted to a value below 7.0; and drying the treated material at temperatures above 220 F. I

2. The process of claim 1 in which the polyaziridinyl compound is tris-l-aziridinyl phosphine oxide.

3. The process of claim 1 in which the polyaziridinyl compound is 1,6-bis-(N-ethylenecarbamido) hexane.

4. The process of claim 1 in which the polyaziridinyl compound is 2,4-bis-(N-ethylenecarbamido) toluene.

5. A durably antistatic shaped hydrophobic polymeric mate-rial obtained by treating said material according to the process of claim 1.

6. A durably antistatic shaped hydrophobic polymeric material obtained by treating said material according to the process of claim 2.

7. A durably antistatic shaped hydrophobic polymeric material obtained by treating said material according to the process of claim 3.

8. A durably antistatic shaped hydrophobic polymeric material obtained by treating said material according to the process of claim 4.

References Cited by the Examiner UNITED STATES PATENTS 2,891,877 6/1959 Chance et al 117-l36 2,901,444 8/1959 Chance et a1 1l7136 X 2,982,751 5/1961 Anthes 117-139.5 X 3,021,232 2/1962 Pretka. 3,070,552 12/1962 Tesoro et al. 117139.50 X

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner. 

1. THE PROCESS OF IMPARTING DURABLE ANTISTATIC PROPERTIES TO A SHAPED HYDROPHOBIC POLYMERIC MATERIAL FOR REDUCING THE TENDENCY OF THE MATERIAL TO ACCUMULATE STATIC ELECTRICITY WHICH COMPRISES APPLYING TO THE HYDROPHOBIC MATERIAL AN AQUEOUS COMOPOSITION CONTAINING: (A) A SOLUBLE POLYTERTIARY AMINE HAVING THE GENERAL FORMULA 